Circumference - All

Circumference can be thought of as the "perimeter" of a circle or the distance around a circle. Since pi is the ratio of circumference to diameter, circumference can be calculated by multiplying the circle's diameter by pi. Another formula substitutes d = 2r, where one diameter equals two radii, and C = 2(r)(pi). Related topics include area of a circle, arc length, and parts of a circle.